Spinal fixation device for immobilizing at least two adjacent vertebrae includes fixing piece in the form of a ring having a central passage through which connecting bar is inserted, and opening through which bone screw element is inserted

摘要

The immobilization device includes two fixing pieces (28) through the central passage (36) of which a connection bar is introduced, with the bar being fixed in position by an intermediate semispherical part and a bone screw clamp element. The fixing piece is in the form of a ring having a lateral wall (34) surrounding the central passage (36) and having a first opening for receiving a threaded or bayonet clamping element. The fixing piece also includes a second opening (40) having first and second parts (46,48), with the first part having an edge (50) for passage of a fixing bone screw. The second part (48) permits free passage of the head of the screw. The axial passage (36) can receive an end of the fixing piece and the head of the screw, so that the screw head can be freely introduced into the axial passage and via actuation of a clamping piece, the end of the fixing piece and the screw head can be immobilized.